The prior art is already aware of various apparatus for adjusting the clearance between the reel and a bedknife in a lawn mower. In some instances, the bedknife is the movable member, and in other instances, the reel is the movable member. For instance, in U.S. Pat. No. 3,187,492, the bedknife is movable through a threaded adjustment for establishing the position of the knife relative to the reel. Also, U.S. Pat. No. 3,106,813 shows adjustment of the bedknife to the reel. U.S. Pat. Nos. 3,685,265 and 4,345,419 show movement of the reel relative to the bedknife. Further, U.S. Pat. No. 4,516,388 shows the application of hydraulics for moving the bedknife relative to the reel to establish the clearance therebetween. Also, U.S. Pat. No. 2,789,712 shows hydraulic apparatus for positioning a tractor shovel.
The present invention differs from the prior art in that it provides for an adjustment of one of the two elements in the reel and bedknife arrangement, whereby the adjustment is accurate and readily accomplished and can be made according to a desired or selected clearance. In the specific embodiments herein, the adjustment is accomplished through a lost-motion type of arrangement where the desired clearance can be established in the method and apparatus, and it can then be related to the adjustable positioning of one of the two elements relative to the other of the two elements, to establish the desired clearance between those two cutting elements.
In achieving the adjustments, one can select the desired clearance, in the field, and the two cutting elements are then brought into contact. Upon releasing of an actuating means which brought the elements into contact, the previously established and desired clearance becomes present between the two elements. In the present embodiments, reliance is not made totally on hydraulics, and thus hydraulic leakage is not at all a factor in the method and apparatus employed herein.
The present invention provides for an on-the-job adjustment or setting, in accordance with the desires of the operator. Also, the entire system is capable of releasing the reel for sharpening the bedknife, and when debris, such as sticks and stones, become lodged between the bedknife and the reel, thereby avoiding dulling or damage to the cutting elements. Further, the present invention provides for minute dimensional adjustments, such as 0.001 to 0.003 inches, to provide for the optimum adjustment and avoid excessive wear between the respective cutting edges and yet assure that the grass will be well mowed.
Still further, this invention provides a way to set the clearance in a manner independent of utilizing displacement of a certain quantity of hydraulic fluid.